The present invention relates generally to an apparatus for processing air in an enclosure and more particularly to an interface for interconnecting a thermostat and an electronically commutated motor operating as a part of an air moving system.
Air conditioning apparatus utilizing an electronically commutated motor ("ECM") are presently available. In general terms, these ECM air moving systems provide processed air to an enclosure at a predetermined, relatively constant air flow rate, usually specified in cubic feet per minute ("CFM"). The details of one such system are described in U.S. Pat. Nos. 4,806,833; 4,540,921; 4,169,990; and 4,005,347; the teachings thereof are incorporated herein by reference.
More specifically, the speed of the ECM is varied to provide the predetermined CFM flow of processed air to the enclosure. This is in contrast to the more conventional, fixed speed blower mechanisms in which the flow rate of processed air varies with direct static pressure.
An ECM system offers several advantages. The first and most significant is efficiency, particularly at low speeds. An ECM system can be forty percent more efficient than a conventional tapped induction motor system, providing in addition more than twice the range of operational speeds. Second, the efficient nature of the ECM system is self-maintained, i.e., it is not affected by system conditions such as dirty air filters. The system continuously adjusts the speed of the ECM to provide the desired CFM. Third, the ECM system lends itself to simple installation while maintaining a high degree of precision for a given air volume application. That is, the ECM system eliminates much of the "guess work" associated with any given installation and the appropriate blower speeds.
The air processing apparatus, as a whole, and the ECM system, in particular, are responsive to a thermostat located within the enclosure. The presently available thermostats vary in kind and operation, but usually provide a series of 24 volt (RMS) AC signals.